Make format-diff.sh locale-independent (#9079)

Summary:
Force POSIX locale for calls to 'git remote' that might have
locale-dependent formatting, as shown in facebook/rocksdb#8731 comment

Pull Request resolved: facebook/rocksdb#9079

Test Plan:
manual (haven't tried on a machine with non-english default
locale)

Reviewed By: ltamasi

Differential Revision: D31943092

Pulled By: pdillinger

fbshipit-source-id: 7dbe5915824f39f73b412cc3d1a86a2521cf76c1

build_tools/format-diff.sh

@@ -127,11 +127,11 @@ uncommitted_code=`git diff HEAD`
 if [ -z "$uncommitted_code" ]
 then
   # Attempt to get name of facebook/rocksdb.git remote.
-  [ "$FORMAT_REMOTE" ] || FORMAT_REMOTE="$(git remote -v | grep 'facebook/rocksdb.git' | head -n 1 | cut -f 1)"
+  [ "$FORMAT_REMOTE" ] || FORMAT_REMOTE="$(LC_ALL=POSIX LANG=POSIX git remote -v | grep 'facebook/rocksdb.git' | head -n 1 | cut -f 1)"
   # Fall back on 'origin' if that fails
   [ "$FORMAT_REMOTE" ] || FORMAT_REMOTE=origin
   # Use main branch from that remote
-  [ "$FORMAT_UPSTREAM" ] || FORMAT_UPSTREAM="$FORMAT_REMOTE/$(git remote show $FORMAT_REMOTE | sed -n '/HEAD branch/s/.*: //p')"
+  [ "$FORMAT_UPSTREAM" ] || FORMAT_UPSTREAM="$FORMAT_REMOTE/$(LC_ALL=POSIX LANG=POSIX git remote show $FORMAT_REMOTE | sed -n '/HEAD branch/s/.*: //p')"
   # Get the common ancestor with that remote branch. Everything after that
   # common ancestor would be considered the contents of a pull request, so
   # should be relevant for formatting fixes.